Electronic circuits may include passive circuit elements, such as resistors and capacitors, and more complex, actively-controlled circuit elements which may provide logic and control functions. An example of an actively-controlled circuit element is a metal oxide semiconductor field effect transistor (MOSFET), which may be controlled to perform a switching function, e.g., turned on and off, or controlled in a linear fashion, e.g., voltage across the MOSFET or current flowing in the MOSFET may be controlled over a continuous range of values.
Circuit elements may be formed as regions of materials on a substrate as part of an integrated circuit. Alternatively, circuit elements may be commercially available as discrete passive and active devices mounted on a circuit board using conventional soldered leads or surface mounted contact pads.
Some circuit components may serve secondary services or functions for primary circuit components. For example, a power converter circuit may be considered a primary circuit, while a ripple filter component coupled to the output of the power converter may provide a secondary service function. Primary circuit components may be sold as commercial products, and service functions may be provided by components that are sold and mounted separately. Alternatively, one or more service functions may be included directly in a primary circuit component.